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Outdoor and Indoor Air Pollution

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  1. Outdoor and Indoor Air Pollution Patrick L. Kinney, Sc.D. Associate Professor Columbia University plk3@columbia.edu

  2. Overview • The natural atmosphere • Outdoor pollutants and their sources • Indoor air pollution • Health effects of air pollution • Measurement of particle pollution • Climate change

  3. Vertical structure of the atmosphere

  4. Troposphere • Lowest 10 km of atmosphere • Contains 75% of the atmospheric mass • The layer in which most weather phenomena occur, e.g., frontal passage, storms, winds • The layer in which most air pollution problems occur • Energy balance is key factor

  5. Distribution of incoming solar radiation 30% reflected back to space About half absorbed by surface

  6. Air set in motion by: • Absorption of energy at surface followed by transfer of heat to lowest layer of air • Heated parcels become buoyant relative to nearby cooler parcels, thereby rising • Rising of air parcel leaves lower pressure at surface • Dense, cool air moves towards the area of low pressure • Pressure gradient force drives winds

  7. As a warm parcel rises, it expands and cools, resulting in the “normal lapse rate” (– 6.5 ºC/km) of troposphere depicted here.

  8. When the temperature lapse rate becomes “inverted” near the surface in urban areas, high pollution levels are likely to result

  9. A Typical Morning in Denver, Colorado

  10. Worst Case: Inversion in a Valley

  11. Carbon monoxide Sulfur dioxide Nitrogen dioxide Volatile organics Ozone Particulate matter Sulfates, nitrates, organics, elemental carbon, lead and other metals Air Pollutants of Human Health Concern

  12. Colorless, odorless gas Primary pollutant, emitted by incomplete combustion of biomass or fossil fuels Binds strongly with hemoglobin, displacing oxygen Emissions reduction by higher temperature combustion and use of catalytic converters on motor vehicles Carbon Monoxide - CO

  13. Primary pollutant, emitted by combustion of fuels containing sulfur; also metal smelting Irritates upper respiratory tract Converted in atmosphere to acid sulfates Emissions reductions by building taller smoke stacks, installing scrubbers, or by reducing sulfur content of fuel being burned Sulfur Dioxide – SO2

  14. Acid Precipitation Formation

  15. Formed by oxidation of NO, which is produced with high temperature combustion (NO2 is a secondary pollutant) Oxidant that can irritate the lungs and hinder host defense A key precursor of ozone formation Emissions reductions by engine redesign and use of catalytic converters Nitrogen Dioxide – NO2

  16. Products of incomplete combustion, evaporation of liquid fuels, atmospheric reactions, and release from vegetation (both primary and secondary) Wide range of compounds with varying health effects Another key ozone precursor Emissions reductions by high temperature combustion and control of evaporation, e.g., during refueling of cars Volatile Organic Compounds VOCs

  17. Secondary pollutant, formed via photochemical reactions in the atmosphere from NOx and VOC in the presence of sunlight Strong oxidant that damages cells lining the respiratory system Concentrations often highest downwind of source regions Emissions reductions by control of NOx and VOC emissions, especially from motor vehicles Ozone – O3

  18. Mechanisms of Ozone Formation

  19. Regional Air Pollution Mechanisms e.g., Ozone and Acid Precipitation

  20. Products of combustion, atmospheric reactions, and mechanical processes Wide range of particle sizes Wide range of physical/chemical properties Wide range of health impacts, including premature death Control by filtration, electrostatic precipitation, and reduction of precursor gases Particulate Matter - PM

  21. Distribution of particle mass at various particle diameters for a typical urban air sample

  22. Particle size distributions differ in urban and rural areas

  23. Particle deposition in the respiratory system is a strong function of particle diameter

  24. Motor Vehicles represent a major source category for several air pollutants (CO, NO2, VOCs, O3, PM)

  25. Figure 3.2 Trends in estimated U.S. Lead Emissions

  26. Figure 3.3 Trends in U.S. Ambient Lead Concentrations

  27. Combustion is principal source: cooking, smoking, heating Dilution and dispersion are limited, especially nearest the source Pollutants of greatest importance include: CO, NO2, PM, VOCs Indoor concentrations often far higher than outdoors, even in urban areas Those who spend the most time indoors near the source will be most impacted Indoor Air Pollution

  28. The most local form of air pollution: indoor combustion of biomass in India

  29. •About half the world ’s households use unprocessed solid fuels for cooking,ranging roughly from near zero in developed countries to more than 80%in China,India,and Sub-Saharan Africa (Holdren et al.,2000). •In simple small-scale devices,such as household cookstoves, solid fuels have rather large emission rates of a number of important health-damaging airborne pollutants including respirable particulates,CO,dozens of PAHs and toxic hydrocarbons,and, depending on combustion and fuel characteristics, nitrogen and sulfur oxides. •A large,although uncertain,fraction of such stoves are not vented,i.e.do not have flues or hoods to take the pollutants out of the living area. •Even when vented to the outdoors,unprocessed solid fuels produce enough pollution to significantly affect local pollution levels with implications for total exposures (Smith et al.,1994).As cookstoves are essentially used everyday at times when people are present,their exposure effectiveness (or intake fraction)is high,i.e.the percentage of their emissions that reach people ’s breathing zones, is much higher than for outdoor sources(Smith, 2002; Bennett et al.,2002). •The individual peak and mean exposures experienced in such settings are large by comparison with WHO guidelines and national standards. From: Kirk Smith, Indoor Air 2002;12:198 .207

  30. For comparison: US annual PM2.5 standard is 15 ug/m3

  31. Table 4.3. Indoor particle air pollution from biomass combustion in developing countries: partial list of studies of individual breathing area concentrations (women during cooking, unless otherwise stated) (Smith 1996).

  32. Albalak R. et al., Environ. Sci. Technol. 2001, 35, 2650-2655

  33. Historical experience provides strong evidence for causal relationship between air pollution and premature death Modern epidemiology studies have consistently found significant associations Two primary epidemiologic study designs: Time series studies of acute effects Cohort or cross-section studies of chronic effects Let’s look at the evidence for particle health effects… Health Effects of Air Pollution

  34. London Killer Fog, December, 1952

  35. London Mid-day inDecember 1952